I haven't experienced the issue with iTunes starting on bluetooth connections, but some people pointed me to this project to deal with it: https://github.com/tombonez/noTunes
You can also set it to start something else (Spotify, whatever) instead
I'm personally just miffed that it's enabled by default. Reminds me of something Microsoft would do (Hey, I see you connected your headphones! Want to launch Groove Music?)
You can also set it to start something else (Spotify, whatever) instead